About 1,500 people chanting for the prime minister's resignation marched through this capital city Friday, accusing the government of working to rig the weekend elections against Bahrain's Shiite majority.

A huge turnout is expected when polls open Saturday after a campaign that has been fierce and dirty, with rally tents vandalized, allegations of secret government funding for favored candidates and torrents of text messages flooding mobile phones. Anonymous messages warn Sunni Muslims to back pro-government candidates against the Shiite Muslim-led opposition or face Iraq-style chaos.

"Wake up Sunnis!" reads one broadly distributed message. "Don't be naive or your fate will be like the Iraqi Sunnis who lost their rights and their lives."

The landmark election in this U.S.-allied Gulf nation will be closely watched by neighboring Arab monarchies, concerned about rising Shiite influence. It is the first time since the constitution was restored in 2001 that the opposition is giving the pro-government candidates a run for their money. The main opposition party boycotted the 2002 elections.

Bahrain is the only Arab nation besides Iraq where Shiites hold a majority of the population, and the impoverished community here has long complained of being squeezed out of power.

"Step down Khalifa," they shouted in unison, referring to Prime Minister Khalifa bin Salman Al Khalifa who has been implicated in an alleged electoral scam that the government has denied.

Recently leaked government documents describe an alleged secret plot to boost the vote for pro-government candidates, mainly Sunni Muslims, by procedures that included handing out citizenship to foreigners.

"The government wants to show the world that we have democracy and everything is normal," said Zahra Moradi, a Shiite who is one of 18 women running for a parliamentary seat. "The government doesn't want real democracy. They want to keep us out."

Nidal Ahmed, 29, a woman in a black abaya gown and black headscarf, punched her fist in the air as she marched along and called for a boycott of the election.

"There are some good people running, but this parliament is fixed," Ahmed shouted. "I want my rights."

With more than 200 Bahrainis vying for the National Assembly's 40-seat lower house, many races appear to be headed for a second-round runoff. Shiite candidates are expected to win a majority of seats, barring widespread fraud.

The government has banned foreign election observers from monitoring the vote. It also imposed a news blackout on the leaked documents alleging attempts to boost the Sunni vote.

Female candidate Latifa al-Gaoud, 50, has already won her seat uncontested, making her the first-ever legislator in the Gulf.

Bahrain and Kuwait are the most democratically advanced of the six Arab Gulf countries, which are ruled by monarchies.

The bewildering array of parties and candidates with wildly differing views has electrified this country of 700,000. About 60 percent are Shiite, but the government is dominated by a Sunni ruling family.

The spectrum ranges from hardline Sunni Islamists, including a jihadist party whose leader was briefly arrested for suspected ties to Al Qaeda, to groups seeking Western-style social liberties in a country that hosts the U.S. Navy's Fifth Fleet.

Buildings have been papered with campaign posters, some bearing the defaced faces of women candidates whose participation has triggered a backlash. Others have accused liberals of drinking alcohol or sexual immorality.

Bahrain political scientist Ali Fakhro worries the vote is deepening the already dangerous divide between Bahrain's privileged Sunnis and downtrodden Shiites.

"We have Shiites standing for themselves and Sunnis standing for themselves," Fakhro said. "We have tribal and familial allegiances. This division is worrying."

Bahrain's 80-seat parliament consists of an elected lower house and an upper chamber appointed by Bahraini King Hamad bin Isa Al Khalifa, who controls most levers of power and can veto parliamentary legislation.

Still, Bahrain has seen a blossoming of social and political freedoms after the dark days of the 1990s, when Shiite unrest brought a bloody police clampdown. In 2002, King Hamad brought back parliamentary elections after a 26-year hiatus. Bahrain's first-ever parliament was elected in 1973 but dissolved in 1975.

The 2002 elections were boycotted by the mainly Shiite opposition and resulted in a Sunni-dominated parliament stocked with conservative Muslims, including some with radical beliefs.

Analysts expect a 70 percent turnout, far larger than the 53 percent turnout in 2002.